Furniture levelling device

ABSTRACT

Provided is a device for adjusting the effective length of a table leg. The device includes an upper and a lower member that is rotatably associated with one another and are biased apart by spring means, the upper member including a first downwardly directed ramp spaced apart from a second ratchet ramps associated with the lower member by a wall. The upper member includes one or more pawls adapted to run in the channel between the ramps, and including a formation adapted to engage the ratchet when the desired effective length of the leg plus device has been adjusted.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a device for adjusting the effective length of a leg of a multi-legged table and particularly a four-or-more legged table; but is also applicable to other articles of furniture such as beds, chairs and the like.

BACKGROUND ART

It is a source of annoyance and frustration that tables, in restaurants in particular, assume a rocking or wobbling tendency due to irregularities in the floor which cause one or more of the legs to lose contact with the floor. Any attempt to overcome this problem by moving the table is usually unsuccessful and many diners resort to the use of wads of folded paper, wedges and the like under one of the legs that does not contact the floor, which is sometimes successful but often results in paper and wedges littering the floor after a while with the recurrence of the nuisance.

Cam mechanisms have been provided which are actuatable with the foot thereby to raise or lower a leg but the perfect position may be lost due to slight movement of the table or of the mechanism.

Several attempts to overcome the problem have been proposed using telescoping legs—for example Japanese Patent 58206333 but these are complicated, difficult to use successfully and aesthetically displeasing.

In U.S. Pat. No. 6,920,834 each leg is telescoping, the inner tubes having keyways and snap locking arrangement in the bottom end of each tube. A dowel pin is provided that is releasable by depressing, sliding the outer tube and snapping the dowel pin into a hole when the length is correct.

In U.S. Pat. No. 6,186,453 a foot-adjustable leveller has a threaded bolt for upward insertion into the end of a leg. A foot is formed at the base with a disc that can be rotated by foot to raise or lower the bolt with resulting adjustment of the device.

It is important that the adjusting mechanism is positively locked in the desired position and it is also important that the adjusting device is easily operated if the table is moved. However, as far as the Applicant is aware, even the most sophisticated arrangements to date have been unsuccessful in regard to permanency of the adjustment.

In U.S. Pat. No. 729,074 a device is described which has an upper and lower members connected for relative rotation and each having a ramp in opposing senses so that rotation causes the ramps to move over each other to cause raising or lowering of the leg due to the corresponding expansion or contraction of the upper and lower members. The friction between the ramps is beneficial in maintaining a sort of permanency but it does not provide the permanency to which the present invention is directed. Nor does it provide the ease of operation and the simple arrangement of the present invention.

A modification of the latter invention is the provision of hydraulic or pneumatic means to be located between the upper and the lower members so that a degree of automatic adjustment is possible but the hydraulic or pneumatic means tends to be overcome by changes in the pressure being applied to the table.

DISCLOSURE OF THE INVENTION

According to the invention a device for adjusting the effective length of a leg of a table or other article of furniture includes an upper and a lower member that are relatively rotatable and are biased apart by spring means, the upper member being associated with a first ramp or ramps that are directed downwards to constitute a wall or walls spaced apart from a second ratchet ramp/s associated with the lower member, the upper member including one or more pawls adapted to run in the channel between the ramps, the pawl/s including a formation adapted to engage the ratchet when the desired effective length of the leg plus device has been adjusted.

The pawl/s may include a first smooth or curved zone to provide minimum friction with the first ramp and a pointed zone for engagement with the ratchet. The pawl/s may be located on the inside of the upper member and may be integrally moulded therewith.

In a preferred form of the invention the device includes an intermediate member that includes the first ramp/s, and that is non-rotatable with the lower member.

It is preferred that two or more corresponding ramps are provided on each of the members and in a specific example three identical and connecting ramps are provided in series on each member in the configuration of saw teeth if laid flat, as will be explained in more detail below. Gaps or passageways are provided to permit the pawls to pass into the series of channels during assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is described below with reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of a device according to the invention,

FIG. 2 is an angled under view of the partly assembled device,

FIG. 3 is an angled side view of FIG. 2,

FIG. 4 is a sectional side view of the device, and

FIG. 5 is a simulated laid out flat view of the series of channels between the ramps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The device of the embodiment includes an upper member 10, a lower member 12 and an intermediate member 14.

The upper member has a larger inside diameter than the intermediate and the lower members and is able to be rotated by virtue of the knurls 16.

The intermediate member has a hollow annulus 18 that receives the lower portion of a spring 20 that is accommodated in the upper member as shown in FIG. 4. A series of ramps 22 depend downwardly from the intermediate member and reference is directed to FIG. 5 in this respect.

The lower member also has a series of ramps 24 that are ratcheted, and reference is again directed to FIG. 5.

Pawls 25 (only one is visible in FIG. 3 and two in FIG. 4) extend through the openings 26 in the intermediate member so that the pawls can be located in the channels defined between the ramps 22 of the upper member and 24 of the lower member.

The assembled device is secured into a formation 28 associated with a leg of a table by means of a bolt element 30, and the members are joined by means of a nut-and-bolt (not shown) or other means of joining. It will be appreciated that only one leg of a four-legged table or other furniture need to be adjusted and it will also be appreciated that dummy devices may be provided for the other three legs for aesthetic purposes.

In operation in the event of the table being unstable due to floor irregularities, the mass of the table as exerted through the formation 24 thereby causing the pawls to rise out of the ratchet and to travel along the ramps 22 of the upper member until the base of the lower portion contacts the floor when the pawls will fall into the respective ratchet. If the situation involves a raised irregularity of the floor and pawls will be released from the ratchets and move along the ramps 22 to the position of rest of the device. Alternatively, or in addition, the upper member may be rotated to secure the same position.

Referring to FIG. 5, the ramps are laid out flat for descriptive purposes. If the upper member is rotated the pawl shown will first move from the position 30 to a position 32 and thence will fall into the lowermost position in the next channel 34. 

1. A device for adjusting the effective length of a leg of a table or other article of furniture, the device including an upper and a lower member that are rotatably associated with one another and biased apart by spring means, characterised in that the lower member includes at least one downwardly directed ramp, spaced apart from a second ratchet ramp by a wall, to form a channel, the upper member including at least one pawl adapted to run in the channel between the ramps, the pawl including a formation adapted to engage the ratchet when the desired effective length of the leg plus device has been adjusted.
 2. A device as claimed in claim 1 characterised in that the pawl includes a first smooth or curved zone to provide minimum friction with the first ramp and a pointed zone for engagement with the ratchet.
 3. A device as claimed in claim 1 characterised in that the pawl is located on the inside of the upper member.
 4. A device as claimed in claim 3 characterised in that the pawl is integrally moulded with the upper member.
 5. A device as claimed in claim 1 characterised in that the upper member includes two pawls.
 6. A device as claimed in claim 1 characterised in that the device includes an intermediate member that includes the downwardly directed ramp, and that is non-rotatable with the lower member.
 7. A device as claimed in claim 1 characterised in that two or more corresponding ramps are provided on each of the members.
 8. A device as claimed in claim 7 characterised in that three identical and connecting ramps are provided in series on each member in the configuration of saw teeth if laid flat. 